TEHRAN, Iran — Iran vowed Tuesday to push ahead with uranium enrichment, a day after the U.N. Security Council passed a third round of sanctions that Tehran called "worthless" and politically biased.

The council approved the measures in a 14-0 vote, but unity among the major powers faltered Tuesday when Russia and China blocked an attempt by Western nations to introduce a resolution on Iran's nuclear defiance at a meeting of the U.N. nuclear watchdog agency.

The dispute reflected the often contentious relations between the West and Russia and China about how to deal with Iran's refusal to suspend enrichment and meet other Security Council demands aimed at ensuring its nuclear program isn't trying to produce atomic weapons.

The sanctions approved Monday ordered a freeze on assets of additional Iranian officials and companies with links to the country's nuclear and missile programs and banned for the first time trade with Iran in some goods that have both civilian and military uses.

"This resolution is contrary to the spirit and articles of the International Atomic Energy Agency. It has been issued based on political motivations and a biased approach. It is worthless and unacceptable," Foreign Ministry spokesman Mohammad Ali Hosseini was quoted as saying by Iran's official news agency.

Zalmay Khalilzad, the U.S. ambassador to the United Nations, told reporters in New York on Tuesday that Tehran's response meant the Security Council had taken appropriate action.

"That shows that they don't like what has happened, which means that we've done the right thing," Khalilzad said.